Hydraena cameroconvexa, Perkins, 2022

Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), Zootaxa 5203 (1), pp. 1-66 : 26

Hydraena cameroconvexa , new species

Figs. 5 , 32 (habitus), 32 (aedeagus), 41 (map)

Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. NW Yaounde, Isali River nr. Nouma, 2.i.1983, leg. P. D. Perkins ” ( MCZ).

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the large body size (ca. 1.74 mm, largest known in Cameroon), the pronotum with sides markedly arcuate over middle 1/3, the oval, transversely quite convex elytra, the very wide P1 and P2, the plaques widely separated carinate lines, and the aedeagus ( Fig. 32 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.74/0.79; head width 0.42; pronotum 0.42/0.58, PA 0.47, PB 0.48; elytra 1.05/0.79. Habitus as illustrated ( Fig. 32 ). Pronotum with sides markedly arcuate over middle 1/3, sides more strongly sinuate posterior to middle than anterior to middle. Frons finely and moderately sparsely punctulate, punctures ca. 1xef, interstices ca. 1–3xpd, shining. Pronotum coarsely densely punctate in anterior and posterior 1/3, interstices ca. 1xpd, shining; disc convex, very finely very sparsely punctulate, interstices ca. 3–6xpd, shining. Punctures of clypeus very fine, sparse on disc, interstices shining, very dense, dull laterally. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin emarginate over middle 1/2; anterolateral pronotal foveae deep; posterolateral and posterosubmedial pronotal foveae very shallow.

Elytra oval, transversely quite convex, posterior declivity abrupt, summit of at or very near midlength; lateral explanate margins wide; punctures coarse, on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, each puncture with very short and very fine seta. Intervals not raised, width ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another.

Venter: Mentum finely sparsely punctulate, shining. Postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.2/1/1. P1 and P2 very wide. P2 l/w ca. 1/1, sides parallel, apex blunt. Plaques widely separated carinate lines, located at sides of deep median depression. AIS very wide, width at straight posterior margin ca. 1.2x P2. All tibiae slender. Protibia very slightly arcuate. Meso- and metatibiae straight. Abdominal apex asymmetrical, with deep apicomedian notch.

Distribution. Currently known only from the type locality ( Fig. 41 ).

Etymology. Named in reference to the known distribution, and to the convex dorsum.

Figures

FIGURE 5. Dorsal habitus of Cameroonian species of Hydraena in Aedeagal Species Group 5.

FIGURE 32. Hydraena cameroconvexa, new species, habitus and aedeagus of holotype.

FIGURES 39–41. Geographical distributions of Cameroonian Hydraena.